The "Limited Time Magic" program will include impromptu concerts, dance parties, colored lighting, character meet-and-greets, new menu and merchandise items and other events at Disneyland in Anaheim, Calif., and Disney World in Lake Buena Vista, Fla., near Orlando.

Guests might also be asked to vote on which characters they'd like to see or be sent on scavenger hunts with hints to figure out what's new or different.

"It's a fun, lighthearted, new way to get people engaged," Leslie Ferraro, executive vice president of global marketing and sales for Walt Disney Parks and Resorts, said at a news conference.

Disney erected a 25-foot-tall castle made of ice in Times Square to symbolize the fleeting nature of the weekly surprises, and water ran down the turrets as the ice melted. Each "Limited Time Magic" theme will last a week. Plans include celebrations of July Fourth, "Pirate Week," 3-D chalk art, "Long Lost Friends Week" featuring lesser-known Disney characters. A Valentine's Day celebration will feature pink and red lighting on Disney castles and romantic candlelit dinners in park restaurants.

Other Disney park news this year includes the continuing expansion of Fantasyland at Disney World's Magic Kingdom. The Fantasyland project, which is the largest expansion in the park's 41-year history, began in March with the first of two Dumbo rides taking flight and is expected to be completed in 2014.